Zhao Xiao-Yan, An Dong-Zi, Liu Man-Li, Ma Jia-Xin, Ali Wajid, Zhu Hao, Li Ming, Ai Xiao-Jun, Nasir Zaheer Ahmad, Alcega Sonia Garcia, Coulon Frederic, Yan Cheng
School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China; Hubei Key Laboratory of Environmental Water Science in the Yangtze River Basin, China University of Geosciences, Wuhan 430074, PR China.
China Construction Eco-Environmental Group Co., Ltd., Beijing 100037, PR China.
Sci Total Environ. 2022 Dec 10;851(Pt 1):158106. doi: 10.1016/j.scitotenv.2022.158106. Epub 2022 Aug 18.
Aeration tanks from activated sludge wastewater treatment plants (WWTPs) can release a large amount of bioaerosols that can pose health risks. However, risk characterization of bioaerosols emissions form wastewater treatment plants is currently not systematically carried out and still in its infancy. Therefore, this study investigated emission characteristic of two indicator model bioaerosols Staphylococcus aureus and Escherichia coli, emitted from aeration tanks of a municipal WWTP. Monte Carlo simulation was then used to quantitatively assess microbial risk posed by different aeration modes under optimistic and conservative estimates. Further to this, two different exposure scenarios were considered during 3 days sampling campaign in autumn and winter. Results showed that the bioaerosol concentration from microporous aeration tank (20-262 CFU m) was one order of magnitude lower than rotating disc aeration tank. Average aerosolization rate was 7.5 times higher with mechanical aeration mode. Health risks of exposed populations were 0.4 and 9.6 times higher in winter than in autumn for E. coli and S. aureus bioaerosol, respectively. Health risks of staff members were 10 times higher than academic visitors. Interesting results were observed for academic visitors without personal protective equipment (PPE) respectively exposed to S. aureus and E. coli bioaerosol in autumn and winter: while the derived infection risk met the United States Environmental Protection Agency (U.S. EPA) benchmark under optimistic estimation, the disease risk burden was over the World Health Organization (WHO) benchmark under conservative estimation. These revealed that only satisfying one of the two benchmarks didn't mean absolute acceptable health risk. This study could facilitate the development of better understanding of bioaerosol quantitative assessment of risk characterizations and corresponding appropriate risk control strategies for wastewater utilities.
活性污泥污水处理厂（WWTPs）的曝气池会释放大量可能构成健康风险的生物气溶胶。然而，目前尚未系统地对污水处理厂生物气溶胶排放进行风险特征描述，该领域仍处于起步阶段。因此，本研究调查了某城市污水处理厂曝气池排放的两种指示性模型生物气溶胶——金黄色葡萄球菌和大肠杆菌的排放特征。随后，采用蒙特卡洛模拟在乐观和保守估计下定量评估不同曝气模式带来的微生物风险。此外，在秋冬为期3天的采样活动中考虑了两种不同的暴露场景。结果表明，微孔曝气池的生物气溶胶浓度（20 - 262 CFU/m）比转盘曝气池低一个数量级。机械曝气模式下的平均雾化率高7.5倍。对于大肠杆菌和金黄色葡萄球菌生物气溶胶，冬季暴露人群的健康风险分别比秋季高0.4倍和9.6倍。工作人员的健康风险比学术访客高10倍。有趣的是，在秋冬分别暴露于金黄色葡萄球菌和大肠杆菌生物气溶胶且未佩戴个人防护装备（PPE）的学术访客中观察到：虽然在乐观估计下得出的感染风险符合美国环境保护局（U.S. EPA）的基准，但在保守估计下疾病风险负担超过了世界卫生组织（WHO）的基准。这些结果表明，仅满足两个基准中的一个并不意味着健康风险绝对可接受。本研究有助于更好地理解生物气溶胶风险特征的定量评估以及为污水处理设施制定相应的适当风险控制策略。
